This invention relates generally to data storage systems, and more particularly to data storage systems having redundancy arrangements to protect against total system failure in the event of a failure in a component or subassembly of the storage system.
As is known in the art, large mainframe computer systems require large capacity data storage systems. These large main frame computer systems generally include data processors which perform many operations on data introduced to the computer system through peripherals including the data storage system. The results of these operations are output to peripherals, including the storage system.
One type of data storage system is a magnetic disk storage system. Here a bank of disk drives and the main frame computer system are coupled together through an interface. The interface includes CPU, or xe2x80x9cfront endxe2x80x9d, controllers (or directors) and xe2x80x9cback endxe2x80x9d disk controllers (or directors). The interface operates the controllers (or directors) in such a way that they are transparent to the computer. That is, data is stored in, and retrieved from, the bank of disk drives in such a way that the mainframe computer system merely thinks it is operating with one mainframe memory. One such system is described in U.S. Pat. No. 5,206,939, entitled xe2x80x9cSystem and Method for Disk Mapping and Data Retrievalxe2x80x9d, inventors Moshe Yanai, Natan Vishlitzky, Bruno Alterescu and Daniel Castel, issued Apr. 27, 1993, and assigned to the same assignee as the present invention.
As described in such U.S. Patent, the interface may also include, in addition to the CPU controllers (or directors) and disk controllers (or directors), addressable cache memories. The cache memory is a semiconductor memory and is provided to rapidly store data from the main frame computer system before storage in the disk drives, and, on the other hand, store data from the disk drives prior to being sent to the main frame computer. The cache memory being a semiconductor memory, as distinguished from a magnetic memory as in the case of the disk drives, is much faster than the disk drives in reading and writing data.
The CPU controllers, disk controllers and cache memory are interconnected through a backplane printed circuit board. More particularly, disk controllers are mounted on disk controller printed circuit boards. CPU controllers are mounted on CPU controller printed circuit boards. And, cache memories are mounted on cache memory printed circuit boards. The disk controller, CPU controller and cache memory printed circuit boards plug into the backplane printed circuit board. In order to provide data integrity in case of a failure in a controller, the backplane printed circuit board has a pair of buses. One set the disk controllers is connected to one bus and another set of the disk controllers is connected to the other bus. Likewise, one set the CPU controllers is connected to one bus and another set of the CPU controllers is connected to the other bus. The cache memories are connected to both buses. Each one of the buses provides data, address and control information.
In accordance with the present invention, an interrupt request controller is provided for processing a plurality of interrupt logic signals. The controller includes: a programmable bit masking section fed by the interrupt logic signals, adapted to mask selected ones of the interrupt signals; a interrupt priority section fed by the programmable mask section for coupling unmasked ones of the interrupt signals to a plurality of outputs selectively in accordance with a predetermined priority criteria.
In one embodiment, the request controller processing a plurality of interrupt logic signals and includes: a programmable section fed by the interrupt signals, for selecting assertion sense and/or assertion type of each one of the interrupt signals.
In accordance with one feature of the invention, an interrupt request controller is provided for processing a plurality of interrupt logic signals. The controller includes: a programmable section fed the interrupt signals, for storing a bit for each one of the interrupt logic signals representative of whether the logic state of the interrupt logic signal should be, or should not be, inverted and for producing a corresponding output logic interrupt signal in accordance therewith.
In accordance with another feature of the invention, an interrupt request controller is provided for processing a plurality of interrupt logic signals. The controller includes: a programmable section fed the interrupt signals, for storing a bit for each one of the interrupt logic signals representative of whether the logic state of the interrupt logic signal should remain as an edge or be converted to a level and for producing a corresponding output logic interrupt signal in accordance therewith.
In accordance with still another feature of the invention, an interrupt request controller is provided for processing a plurality of interrupt logic signals. The controller includes: a programmable section fed by the interrupt signals, for selecting assertion sense and/or assertion type of each one of the interrupt signals; a programmable bit masking section coupled to the programmable assertion sense/assertion type section, adapted to mask selected ones of the interrupt signals; a interrupt priority section fed by the programmable mask section for coupling unmasked ones of the interrupt signals to a plurality of outputs selectively in accordance with a predetermined priority criteria.
In one embodiment, the programmable assertion sense and/or assertion type section includes for each one of the interrupt logic signals an interrupt sense register for storing a bit representative of whether the logic state of the interrupt logic signal should be, or should not be, inverted.
In one embodiment, the programmable assertion sense and/or assertion type section includes for each one of the interrupt logic signals, an interrupt type register for storing a bit representative of whether the logic state of the interrupt logic signal should remain as an edge or be converted to a level.